Weighing in on Axles
Matt Sutter, via CarCraft.com: I really enjoyed your article on the budget 10-bolt buildup in the March issue. Would you happen to know how much the 8.5-inch 10-bolt rearend weighs? I think the GM 12-bolt is around 186 pounds and a Ford 9-inch is around 177 pounds. I'm trying to decide what to build.
Terry McGean: Your question got us thinking around the offices, Matt. First of all, you listed the 12-bolt as being heavier than the 9-inch, which we believed was incorrect, but then we couldn't point to a specific source to verify that, so we got out the scales.
First up was the same 10-bolt we'd built in the story you referenced. It's a stock 8.5-inch housing for a Nova/first-gen Camaro filled with an Eaton limited-slip unit and stock-type ring-and-pinion. The only significant weight increase over absolute stock probably comes from the Dutchman 30-spline axles, though the difference is probably less than 10 pounds. With axles but no brakes, our 10-bolt came in at about 160 pounds. Interestingly, when Jeff Smith weighed one of his Chevelle 12-bolts, he came up with 152 pounds, less brakes. The '64-'67 A-body rearends use the same axle length as the early-Camaro rearends, so dimensionally, these two assemblies should be nearly identical. Jeff's axles were stock, and stock 12-bolts use a 30-spline axle, so it would seem that our 30-spline 8.5-inch 10-bolt is a near match, pound for pound.
Jeff then put the 9-inch rearend assembly on the scale, also spec'd for an early Chevelle, and found that without brakes it was a portly 186 pounds. That particular rear used a cast-iron centersection as a stock Ford unit would but had an aluminum pinion support. Additionally, the Ford drum brakes that are typically paired with a 9-inch are larger than the usual 9-inch-diameter GM drums found on Camaros, Chevelles, and so on, and seem to weigh about 4-5 pounds more per pair.
It's no surprise that the Ford 9-inch is weighty; drag racers have been familiar with this penalty for years, making the sacrifice for the increased strength. Aluminum carriers can help shed some of the unwanted bulk, but probably not enough to slim it down to the weight of a 10- or 12-bolt.
Chris, via CarCraft.com: I have an '80 El Camino with a 350 and a Saginaw four-speed. It's been stuck in First gear for a while, and I'm still not sure why. Maybe linkage adjustment, broken bushings, or bad synchros...I don't know. It's not sitting on level ground, so I can't jack it up where it sits. I pushed the clutch in and my friend pulled it with his truck, but the wheels wouldn't move. I know the rearend isn't locked up. I started it up, gave it some gas, and let out the clutch; it grunted really hard, but it won't move. Any ideas? I don't know too much about transmissions, but this is my project car and that's where I need to start.
Terry McGean: Sounds like you've got it stuck in two gears, Chris, and one of them is probably Reverse. This isn't uncommon when the external shift linkage of a manual transmission gets worn. You didn't state whether this was a factory setup ('80 El Caminos were offered with four-speeds from the factory) or something that's been transplanted, but either way, you need to check the linkage. Freeing the trans is likely a simple matter of jiggling the linkage rods under the vehicle; the rods for First/Second and Reverse may actually be bound against each other, since one was probably not fully returned to Neutral before the other was engaged, again the likely result of a worn-out shifter. If you can't get underneath the car, you may be able to partially access the shift linkage from inside after removing the shifter boot.